Numerical control grinding machine for grinding a taper portion of a workpiece

Abstract

In a numerical control grinding machine, a workpiece with a taper portion to be ground is rotatably supported on a swivel table which is mounted on a traverse table to be pivotable about a pivot. For grinding the taper portion, the traverse table is moved to bring a reference end surface of a workpiece into engagement with a measuring device, and a numerical controller detects a deviation of the pivot from a corresponding position in the case of a workpiece model. The numerical controller is in advance given a reference table feed amount, a reference swivel pivot angle and a reference wheel feed amount through which the traverse table, the swivel table and the grinding wheel would be moved respectively after the reference end surface is brought into engagement with the measuring device, to precisely grind a corresponding taper portion of the workpiece model if the same were supported on the swivel table. The numerical controller compensates the reference table feed amount and the reference wheel feed amount for the detected deviation and then, controls movements of said traverse table, the swivel table and the grinding wheel based upon the compensated table feed amount, the reference swivel pivot angle and the compensated wheel feed amount, whereby the taper portion of the workpiece can be ground to a desired dimension at a position spaced from the reference end surface a predetermined distance.

What is claimed is: 
     
       1. A numerical control grinding machine, comprising: a bed;   a traverse table movably mounted on said bed;   a swivel table mounted on said traverse table and pivotable about a pivot secured to said traverse table;   workpiece support means mounted on said swivel table for supporting a workpiece to be rotatable about an axis which extends in the moving direction of said traverse table;   a grinding wheel mounted on said bed and movable toward and away from said workpiece;   a traverse feed device for moving said traverse table;   a swivel feed device for pivotally moving said swivel table about said pivot;   a wheel feed device for moving said grinding wheel toward and away from said workpiece;   a measuring device engageable with a reference end surface of said workpiece for generating a signal when said reference end surface is located, through movement of said traverse table, at a predetermined position in the moving direction of said traverse table; and   a numerical controller for controlling said traverse, swivel and wheel feed devices in response to said signal from said measuring device, said numerical controller including:   first feed control means for controlling said traverse feed device so as to move said traverse table from an original position to a reference detecting position which is determined upon engagement with said reference end surface with said measuring device;   feed amount detection means responsive to said signal for detecting a first feed amount through which said traverse table is moved from said original position to said reference detecting position;   first calculation means for calculating the difference between said first feed amount detected by said feed amount detection means and a first predetermined value, said first predetermined value being indicative of a feed amount through which said traverse table would be moved from said original position to said reference detecting position if a workpiece model were supported by said workpiece support means;   second calculation means for calculating based upon said calculated difference second and third feed amounts through which said traverse table and said grinding wheel are to be moved respectively so that said taper portion of said workpiece can be ground to a desired dimension;   second feed control means for controlling said traverse feed device to move said traverse table by said calculated second feed amount from said reference detecting position;   third feed control means for controlling said swivel feed device to pivot said swivel table by a predetermined angle; and   fourth feed control means for controlling said wheel feed device to move said grinding wheel toward said workpiece by said calculated third feed amount.   
     
     
       2. A numerical control grinding machine as set forth in claim 1, wherein said second calculation means comprises: first compensation means for calculating said second feed amount by compensating a second predetermined value for said calculated difference, said second predetermined value being indicative of a feed amount through which said traverse table would be moved from said reference detecting position to axially position said taper portion of said workpiece model relative to said grinding wheel if said workpiece model were supported by said workpiece support means; and   second compensation means for calculating said third feed amount by compensating a third predetermined value for said calculated difference, said third predetermined value being indicative of a feed amount through which said grinding wheel would be advanced to grind said taper portion of said workpiece model to a desired dimension if said workpiece model were supported by said workpiece support means.   
     
     
       3. A numerical control grinding machine as set forth in claim 2, wherein: said feed amount detection means detects said first feed amount based upon the operational amount of said traverse feed device controlled by said first feed control means.   
     
     
       4. A numerical control grinding machine as set forth in claim 3, wherein: said first compensation means calculates said second feed amount by subtracting said calculated difference from said second predetermined value; and   said second compensation means calculates said third feed amount by substracting from said third predetermined value a component of sine which is calculated based upon said calculated difference and said predetermined angle through which said swivel table is pivoted by said swivel feed device.   
     
     
       5. A numerical control grinding machine as set forth in claim 4, wherein: said grinding wheel is movable in a direction which intersects the moving direction of said traverse table at an acute angle.